title: Survivability of Escherichia coli O157:H7 in mechanically tenderized beef steaks subjected to lactic acid application and cooking under simulated industry conditions.
abstract: Mechanical tenderization improves the palatability of beef; however, it increases the risk of translocating pathogenic bacteria to the interior of beef cuts. This study investigated the efficacies of lactic acid spray (LA; 5 % ), storage, and cooking on the survivability of Escherichia coli O157:H7 in mechanically tenderized beef steaks managed under simulated industry conditions. Beef subprimals inoculated with either high (10(5) CFU/ml) or low (10(3) CFU/ml) levels of E. coli O157:H7 were treated (LA or control) and stored for 21 days prior to mechanical tenderization, steak portioning (2.54 cm), and additional storage for 7 days. Steaks were then cooked to an internal temperature of 55, 60, 65, 70, or 75°C. Samples were enumerated and analyzed using DNA-based methods. Treatment with LA immediately reduced E. coli O157:H7 on the lean and fat surfaces of high- and low-inoculum-treated subprimals by more than 1.0 log CFU/cm(2) (P < 0.05). Storage for 21 days reduced surface populations of E. coli O157:H7 regardless of the inoculation level; however, the populations on LA- and control-treated lean surfaces of high- and low-inoculum-treated subprimals were not different after 21 days (P > 0.05). E. coli O157:H7 was detected in core samples from high-inoculum-treated steaks cooked to 55, 60, or 70°C. Conversely, E. coli O157:H7 was not detected in core samples from low-inoculum-treated steaks, regardless of the internal cooking temperature. These data suggest that LA- and storage-mediated reduction of pathogens on subprimals exposed to typical industry contamination levels (10(1) CFU/cm(2)) reduces the risk of pathogen translocation and subsequent survival after cooking.
authors.affiliation: Department of Animal and Food Sciences, Texas Tech University, Box 42141, Lubbock, Texas 79409, USA.
authors.forename: C C
authors.initials: CC
authors.lastname: Chancey
authors.forename: J C
authors.initials: JC
authors.lastname: Brooks
authors.forename: J N
authors.initials: JN
authors.lastname: Martin
authors.forename: A
authors.initials: A
authors.lastname: Echeverry
authors.forename: S P
authors.initials: SP
authors.lastname: Jackson
authors.forename: L D
authors.initials: LD
authors.lastname: Thompson
authors.forename: M M
authors.initials: MM
authors.lastname: Brashears
mesh_terms: D000818:Animals; D002417:Cattle; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D019453:Escherichia coli O157 / Q000254:growth & development*; D005506:Food Contamination / Q000032:analysis*; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D006801:Humans; D019344:Lactic Acid / Q000494:pharmacology*; D008460:Meat / Q000382:microbiology*; D050296:Microbial Viability; D013696:Temperature; D013997:Time Factors
chemical_list: D019344:Lactic Acid